An industrial robot is officially
defined by ISOas
an automatically controlled, reprogrammable, multipurpose
manipulator programmable in three or more axes that is used
in the workforce. The field of robotics may be
more practically defined as the study, design and use of
robot systems for manufacturing (a top-level definition
relying on the prior definition of robot).

Robots doing vehicle underbody
assembly (KUKA).

Typical applications of robots include
welding, painting, ironing, assembly, pick and place,
packaging and palletizing, product inspection, and
testing, all accomplished with high endurance, speed,
and precision.

Robot
types, features

The most commonly used robot configurations
are articulated robots, SCARA robots and gantry
robots (aka Cartesian Coordinate robots, or x-y-z
robots). In the context of general robotics, most
types of robots would fall into the category of
robot arms (inherent in the use of the word manipulator
in the above-mentioned ISO standard). Robots exhibit
varying degrees of autonomy:

Some robots are programmed to
faithfully carry out specific actions over and
over again (repetitive actions) without variation
and with a high degree of accuracy. These actions
are determined by programmed routines that specify
the direction, acceleration, velocity, deceleration,
and distance of a series of coordinated motions.

Other robots are much more flexible
as to the orientation of the object on which they
are operating or even the task that has to be
performed on the object itself, which the robot
may even need to identify. For example, for more
precise guidance, robots often contain machine
vision sub-systems acting as their "eyes", linked
to powerful computers or controllers. Artificial
intelligence, or what passes for it, is becoming
an increasingly important factor in the modern
industrial robot.

History of
Industrial Robotics in the Work Force

George Devol applied for the first
robotics patents in 1954 (granted in 1961). The
first company to produce a robot was Unimation,
founded by George Devol and Joseph F. Engelberger
in 1956, and was based on Devol's original patents.
Unimation robots were also called programmable
transfer machines since their main use at first
was to transfer objects from one point to another,
less than a dozen feet or so apart. They used hydraulic
actuators and were programmed in joint coordinates,
i.e. the angles of the various joints were stored
during a teaching phase and replayed in operation.
They were accurate to within 1/10,000 of an inch
(note: although accuracy is not an appropriate measure
for robots, usually evaluated in terms of repeatability
- see later). Unimation later licensed their technology
to Kawasaki Heavy Industries and Guest-Nettlefolds,
manufacturing Unimates in Japan and England respectively.
For some time Unimation's only competitor was Cincinnati
Milacron Inc. of Ohio. This changed radically in
the late 1970s when several big Japanese conglomerates
began producing similar industrial robots.

In 1969 Victor Scheinman at Stanford
University invented the Stanford arm, an all-electric,
6-axis articulated robot designed to permit an arm
solution. This allowed it to accurately follow arbitrary
paths in space and widened the potential use of
the robot to more sophisticated applications such
as assembly and welding. Scheinman then designed
a second arm for the MIT AI Lab, called the "MIT
arm." Scheinman, after receiving a fellowship from
Unimation to develop his designs, sold those designs
to Unimation who further developed them with support
from General Motors and later marketed it as the
Programmable Universal Machine for Assembly (PUMA).
In 1973 KUKA Robotics built its first robot, known
as FAMULUS, this is the first articulated robot
to have six electromechanically driven axes.

Interest in robotics swelled in
the late 1970s and many US companies entered the
field, including large firms like General Electric,
and General Motors (which formed joint venture FANUC
Robotics with FANUC LTD of Japan). U.S. start-ups
included Automatix and Adept Technology, Inc. At
the height of the robot boom in 1984, Unimation
was acquired by Westinghouse Electric Corporation
for 107 million U.S. dollars. Westinghouse sold
Unimation to Stäubli Faverges SCA of France in
1988, which is still making articulated robots for
general industrial and clean room applications and
even bought the robotic division of Bosch in late
2004.

Only a few non-Japanese companies
ultimately managed to survive in this market, including
Adept Technology, Stäubli-Unimation, the Swedish-Swiss
company ABB (ASEA Brown-Boveri), the Austrian manufacturer
igm Robotersysteme AG and the German company KUKA
Robotics.

Technical
description

Defining
perimeters

Number of axes two axes
are required to reach any point in a plane; three
axes are required to reach any point in space.
To fully control the orientation of the end of
the arm (i.e. the wrist) three more axes
(roll, pitch and yaw) are required. Some designs
(e.g. the SCARA robot) trade limitations in motion
possibilities for cost, speed, and accuracy.

Degrees of freedom which
is usually the same as the number of axes.

Working envelope the region
of space a robot can reach.

Kinematics the actual
arrangement of rigid members and joints in the
robot, which determines the robot's possible motions.
Classes of robot kinematics include articulated,
cartesian, parallel and SCARA.

Carrying capacity or payload
how much weight a robot can lift.

Speed how fast the robot
can position the end of its arm. This may be defined
in terms of the angular or linear speed of each
axis or as a compound speed i.e. the speed of
the end of the arm when all axes are moving.

Acceleration - how quickly
an axis can accelerate. Since this is a limiting
factor a robot may not be able to reach it's specified
maximum speed for movements over a short distance
or a complex path requiring frequent changes of
direction.

Accuracy how closely a
robot can reach a commanded position. Accuracy
can vary with speed and position within the working
envelope and with payload (see compliance). It
can be improved by Robot calibration.

Repeatability - how well
the robot will return to a programmed position.
This is not the same as accuracy. It may be that
when told to go to a certain X-Y-Z position that
it gets only to within 1 mm of that position.
This would be its accuracy which may be improved
by calibration. But if that position is taught
into controller memory and each time it is sent
there it returns to within 0.1 mm of the
taught position then the repeatability will be
within 0.1 mm.

Motion control for some
applications, such as simple pick-and-place assembly,
the robot need merely return repeatably to a limited
number of pre-taught positions. For more sophisticated
applications, such as welding and finishing (spray
painting), motion must be continuously controlled
to follow a path in space, with controlled orientation
and velocity.

Power source some robots
use electric motors, others use hydraulic actuators.
The former are faster, the latter are stronger
and advantageous in applications such as spray
painting, where a spark could set off an explosion;
however, low internal air-pressurisation of the
arm can prevent ingress of flammable vapours as
well as other contaminants.

Drive some robots connect
electric motors to the joints via gears; others
connect the motor to the joint directly (direct
drive). Using gears results in measurable
'backlash' which is free movement in an axis.
In smaller robot arms with DC electric motors,
because DC motors are high speed low torque motors
they frequently require high ratios so that backlash
is a problem. In such cases the harmonic drive
is often used.

Compliance - this is a
measure of the amount in angle or distance that
a robot axis will move when a force is applied
to it. Because of compliance when a robot goes
to a position carrying it's maximum payload it
will be at a position slightly lower than when
it is carrying no payload. Compliance can also
be responsible for overshoot when carrying high
payloads in which case acceleration would need
to be reduced.

Robot programming
and interfaces

The setup or programming of motions
and sequences for an industrial robot is typically
taught by linking the robot controller to a laptop,
desktop computer or (internal or Internet) network.

Software: The computer is
installed with corresponding interface software.
The use of a computer greatly simplifies the programming
process. Specialized robot software is run either
in the robot controller or in the computer or both
depending on the system design.

Teach pendant: Robots can
also be taught via a teach pendant; a handheld control
and programming unit. The common features of such
units are the ability to manually send the robot
to a desired position, or "inch" or "jog" to adjust
a position. They also have a means to change the
speed since a low speed is usually required for
careful positioning, or while test-running through
a new or modified routine. A large emergency stop
button is usually included as well. Typically once
the robot has been programmed there is no more use
for the teach pendant.

Lead-by-the-nose is a technique
offered by most robot manufacturers but is of dubious
value. While user holds the robot end effector another
person enters a command which de-energizes the robot
and it goes limp. The user then moves the robot
by hand to the required positions or along a required
path while the software logs these positions into
memory. The program can later run the robot to these
positions or along the taught path. This technique
is popular for tasks such as paint spraying.

Others In addition, machine
operators often use human machine interface devices,
typically touch screen units, which serve as the
operator control panel. The operator can switch
from program to program, make adjustments within
a program and also operate a host of peripheral
devices that may be integrated within the same robotic
system. These include end effectors, feeders that
supply components to the robot, conveyor belts,
emergency stop controls, machine vision systems,
safety interlock systems, bar code printers and
an almost infinite array of other industrial devices
which are accessed and controlled via the operator
control panel.

The teach pendant or PC is usually
disconnected after programming and the robot then
runs on the program that has been installed in its
controller. However a computer is often used to
'supervise' the robot and any peripherals, or to
provide additional storage for access to numerous
complex paths and routines.

A robot and a collection of machines
or peripherals is referred to as a workcell, or
cell. A typical cell might contain a parts feeder,
a molding machine and a robot. The various machines
are 'integrated' and controlled by a single computer
or PLC.

Recent and
future developments

As of 2005, the robotic arm business
is approaching a mature state, where they can provide
enough speed, accuracy and ease of use for most
of the applications. Vision guidance (aka machine
vision) is bringing a lot of flexibility to robotic
cells. So we have the arm and the eye, but the part
that still has poor flexibility is the hand: the
end effector attached to a robot is often a simple
pneumatic, 2-position wrench. This doesn't allow
the robotic cell to easily handle different parts,
in different orientations.

Hand-in-hand with increasing off-line
programmed applications, robot calibration is becoming
more and more important in order to guarantee a
good positioning accuracy.

Other developments include downsizing
industrial arms for consumer applications (micro-robotic
arms), manufacture of domestic robots and using
industrial arms in combination with more intelligent
automated guided vehicles (AGVs) to make the automation
chain more flexible between pick-up and drop-off.

Prices of robots will vary with
the features, but are usually from 12,000 USD for
an entry-level model, and as much as 100,000 or
more for a heavy-duty, long-reach robot.